arm64: dts: ti: k3-j784s4-*: Add DSS node

Add DSS node for J784S4 SoC. DSS IP in J784S4
is same as DSS IP in J721E, so same compatible is
being used.
Also add assigned clks for DSS

Signed-off-by: Rahul T R <r-ravikumar@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>